Optical accessories for use in combination with spectacles exist for a wide variety of reasons. Sunglass accessories, for instance, generally permit optimum use of the spectacles under varying lighting conditions. Other optical accessories provide, for example, eye shielding and vision correcting functions.
A number of factors are considered important in constructing such accessories. In this regard, it is desirable to have the optical elements of the accessory positioned in correct superposed relationship to the optical members of the spectacles for proper usage and convenience. In many instances, it is highly desirable to avoid unnecessary movement of the accessory relative to the spectacle frame. Moreover, facilitating quick, easy and reliable mounting and demounting of the accessory are of practical importance. Significantly, it is desirable to have these mounting arrangements as aesthetic as possible. Unaesthetic mounting arrangements, of course, detract appreciably from the commercial appeal of succh accessories. Furthermore, in the highly competitive spectacle accessory field need exists to provide the foregoing features as simply, economically and efficiently as possible.
Mounting arrangements for releasably attaching optical accessories to spectacle frames are significant structural features of these accessories. The following are exemplary of prior art optical accessories and their associated releasable mounting arrangements: U.S. Pat. Nos. 1,348,713; 2,580,859; 2,607,919; 2,696,141; 2,949,609; 2,981,956; 3,092,838; 3,238,005; 3,345,121; 3,453,042; 3,555,563; 3,604,013; 3,741,634; 3,890,037; 3,944,346; 3,981,569; 4,012,129; 4,176,921; 4,253,745; 4,322,138; 4,338,004; 4,402,577; 4,402,578; and 4,405,214.
Known optical accessories exhibit a number of deficiencies in connection with the foregoing enumerated design factors. Moreover, most of such accessories have specially constructed frames to be attached to in order to work effectively. Accordingly, they are not compatible with many kinds of existing frames commercially sold. Furthermore, these specially constructed spectacles often appear unattractive when the accessories are removed therefrom.